The choice between present and future consumption.
On the other hand, given a higher rate of return, people need to save less now to finance a given level of future consumption.
NNP is the amount of goods in a given year which can be consumed without reducing future consumption.
But if he values future consumption, all that extra output might not be worth consuming in its entirety today.
The net effect on future consumption is the elasticity of intertemporal substitution.
These two rates must necessarily be equal, and this equilibrium is brought about by the relative prices of present and future consumption.
It hides whatever it cannot eat for future consumption.
Meat and even skin are often dried over the fire and stored for future consumption.
Increased savings in the current period raises the expected value of future consumption.
Yet increases in saving will also increase the variability (variance) of future consumption.